Prosthetic valve that permits retrograde flow

ABSTRACT

A prosthetic valve for regulating fluid flow through a body vessel is provided. The valve includes an expandable support frame and a valve leaflet, and includes at least one opening that permits a controlled amount of retrograde flow through the valve when the valve is in a closed configuration. A flap disposed adjacent the opening is able to temporarily and substantially close the opening to contribute to the regulation of retrograde flow proceeding through the valve.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Utility applicationSer. No. 10/797,449, filed on Mar. 10, 2004, now U.S. Pat. No. 7,402,171and which claims priority to U.S. Provisional Application Ser. No.60/454,249, filed on Mar. 12, 2003, and U.S. Provisional ApplicationSer. No. 60/488,138, filed on Jul. 16, 2003. The disclosure of each ofthese related applications is hereby incorporated into this disclosurein its entirety.

FIELD OF THE INVENTION

The present invention relates to medical devices. More particularly, theinvention relates to intraluminal valve prostheses.

BACKGROUND OF THE INVENTION

Many vessels in animal bodies transport fluids from one bodily locationto another. Frequently, fluid flows in a unidirectional manner along thelength of the vessel. Varying fluid pressures over time, however, canintroduce a reverse flow direction in the vessel. In some vessels, suchas mammalian veins, natural valves are positioned along the length ofthe vessel and act as one-way check valves that open to permit the flowof fluid in the desired direction and close to prevent fluid flow in areverse direction, i.e., retrograde flow. The valves can change from anopen position in response to a variety of circumstances, includingchanges in the cross-sectional shape of the vessel and the fluidpressure within the vessel.

While natural valves may function for an extended time, some may loseeffectiveness, which can lead to physical manifestations and pathology.For example, venous valves are susceptible to becoming insufficient dueto one or more of a variety of factors. Over time, the vessel wall maystretch, affecting the ability of the valve leaflets to close.Furthermore, the leaflets may become damaged, such as by formation ofthrombus and scar tissue, which may also affect the ability of the valveleaflets to close. Once valves are damaged, venous valve insufficiencymay be present, and can lead to discomfort and possibly ulcers in thelegs and ankles.

Current treatments for venous valve insufficiency include the use ofcompression stockings that are placed around the leg of a patient in aeffort to force the vessel walls radially inward to restore valvefunction. Surgical techniques are also employed in which valves can bebypassed, eliminated, or replaced with autologous sections of veinshaving competent valves.

Minimally invasive techniques and instruments for placement ofintraluminal medical devices have developed over recent years. A widevariety of treatment devices that utilize minimally invasive technologyhas been developed and includes stents, stent grafts, occlusion devices,infusion catheters and the like. Minimally invasive intravasculardevices have especially become popular with the introduction of coronarystents to the U.S. market in the early 1990s. Coronary and peripheralstents have been proven to provide a superior means of maintainingvessel patency, and have become widely accepted in the medicalcommunity. Furthermore, the use of stents has been extended to treataneurysms and to provide occlusion devices, among other uses.

Recently, prosthetic valves that are implantable by minimally invasivetechniques have been developed. Frequently, a graft member is attachedto a support frame and provides a valve function to the device. Forexample, the graft member can be in the form of a leaflet that isattached to a support frame and movable between first and secondpositions. In a first position, the valve is open and allows fluid flowto proceed through a vessel in a first direction, and in a secondposition the valve is closed to prevent fluid flow in a second, oppositedirection. Examples of this type of prosthetic valve are described incommonly owned U.S. Pat. No. 6,508,833 to Pavcnik for a MULTIPLE-SIDEDINTRALUMINAL MEDICAL DEVICE, United States Patent ApplicationPublication No. 2001/0039450 to Pavcnik for an IMPLANTABLE VASCULARDEVICE, and U.S. patent application Ser. No. 10/642,372, filed on Aug.15, 2003, each of which is hereby incorporated by reference in itsentirety. In other examples of prosthetic valves, a tube that terminatesin leaflets is attached to one or more support frames to form a valve.The leaflets open to permit fluid flow in a first direction in responseto fluid pressure on one side of the leaflets, and close to preventfluid flow in a second, opposite direction in response to fluid pressureon opposite sides of the leaflets. An example of this configuration isprovided in U.S. Pat. No. 6,494,909 to Greenhalgh for AN ENDOVASCULARVALVE, which is hereby incorporated by reference in its entirety.

Natural valves can be somewhat ‘leaky’, allowing a relatively smallquantity of fluid to flow in a reverse direction when the valve is in aclosed position. It is believed that this leakiness is beneficial forseveral reasons. For example, it is believed that a small amount ofretrograde flow limits the pooling of blood around the natural valveduring periods of low pressure, which can reduce the formation ofthrombus adjacent the valve leaflets and, therefore, increase theeffective lifetime of the valve.

Prior art prosthetic valves, however, do not permit a controlled amountof retrograde flow. Indeed, most prior art valves have been designed toprevent leakage as much as possible. Accordingly, there is a need for aprosthetic valve that permits a controlled amount of retrograde flow.

SUMMARY OF THE INVENTION

A medical device according to the invention provides a valve forregulating fluid flow through a body vessel. The device is particularlywell-suited for percutaneous delivery through a body vessel to a pointof treatment, and comprises a prosthetic venous valve in an illustrativeembodiment. The valve permits a controlled quantity of retrograde flowto flow through the device when the valve is in its closedconfiguration.

The medical device includes a support frame, such as an endoluminalstent, that has radially compressed and radially expandedconfigurations. The support frame can comprise any suitable supportframe, including self-expandable, balloon expandable, wire, tube, metal,polymeric, composite and other types of support frames known in the art.

The device includes at least one leaflet attached to the supportstructure. The leaflet provides a valve function to the device. In oneembodiment, the leaflet provides the valve function by moving betweenfirst and second positions while remaining attached to the supportframe. In one position, the leaflet substantially blocks the lumen ofthe vessel, while the lumen is substantially open when the leaflet is inthe second position. Thus, the leaflet permits fluid flow through thevessel in a first direction when in the first position, andsubstantially prevents fluid flow through the vessel in a second,opposite direction when in the second position. The leaflet can beformed of a bioremodellable material, such as small intestine submucosa(SIS) or other extracellular matrix (ECM) material.

The device includes an opening that permits a controlled amount of fluidflow through the device in the opposite direction when the valve isclosed. Thus, while the leaflet substantially prevents fluid flow in thesecond, opposite direction, the device includes an opening that allowssome flow of fluid in this direction. Allowing such flow, retrogradeflow, lessens pooling of fluid around the device when the leaflet is inthe closed, or second, position. This is expected to prevent pooling ofblood around the device, which may prevent formation of thrombus andincrease the overall acceptance of the device by a host.

The opening can be defined entirely by the leaflet, or by at least aportion of an edge of the leaflet and a portion of the support frame. Ineither embodiment, a liner can be placed on at least a portion of theopening. The liner provides structural integrity to the perimeter of theopening, and may define structural features that maintain a distancebetween the leaflet and a wall of the vessel. Further, the liner maydefine structural features that facilitate fluid flow through theopening in the second, opposite direction.

The opening is advantageously dimensioned to permit sufficientretrograde flow to achieve the desired effect without destroying thevalve function of the device. In the venous valve embodiments, the totalopen area of the opening can be compared to the total cross-sectionalarea of the vessel lumen. In some embodiments, the total open area ofthe opening is less than the total cross-sectional area of the vessel ata desired point of treatment. In other embodiments, the total open areaof the opening is less than half of the total cross-sectional area ofthe vessel.

The device can include more than one opening that permits a controlledamount of retrograde flow through the device.

A more detailed explanation of the invention is provided by the attacheddrawings and detailed description, which illustrate exemplaryembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a support frame for use in medical devicesaccording to the present invention.

FIG. 1A is an enlarged partially sectioned view of the support frameillustrated in FIG. 1.

FIG. 2 is a perspective view of the support frame illustrated in FIG. 1deployed within a body vessel.

FIG. 3 is a partially sectioned view of the support frame illustrated inFIG. 1 within a delivery device.

FIG. 4 is a partially sectioned view of a body vessel containing amedical device according to a first embodiment of the invention.

FIG. 5 is a partially sectioned view of a body vessel containing themedical device illustrated in FIG. 4 in a closed position.

FIG. 6 is a partially sectioned view of a body vessel containing amedical device according to a second embodiment of the invention.

FIG. 7 is a perspective view of a medical device according to a thirdembodiment of the invention.

FIG. 8 is a perspective view of a medical device according to a fourthembodiment of the invention.

FIG. 9 is a perspective view of a body vessel containing the medicaldevice illustrated in FIG. 8.

FIG. 10 is a perspective view of a medical device according to a fifthembodiment of the invention.

FIG. 11 is an enlarged partial view of a portion of the medical deviceillustrated in FIG. 10.

FIG. 12 is a sectional view of the medical device illustrated in FIG. 10taken along line 12-12.

FIG. 13 is a perspective view of a medical device according to a sixthembodiment of the invention.

FIG. 14 is a perspective view of a body vessel containing the medicaldevice illustrated in FIG. 13.

FIG. 15 is a partially sectioned view of a body vessel containing amedical device according to a seventh embodiment of the invention.

FIG. 16 is a partial top view of a support frame for use in medicaldevices according to the present invention.

FIGS. 17A, 17B, 17C, and 17D are perspective views of medical devicesaccording to the invention.

FIG. 18 is a perspective view of a medical device according to anotherembodiment of the invention.

FIGS. 19A, 19B, 19C, 19D, 19E, and 19F are perspective views of medicaldevices according to the invention.

FIGS. 20A, 20B, 20C, and 20D are perspective views of medical devicesaccording to the invention.

FIG. 21 is a magnified view of a valve leaflet with cut linesillustrating the formation of an opening in the leaflet.

FIG. 22 is a magnified view of a valve leaflet of a medical deviceaccording to an embodiment of the invention.

FIG. 23 is a magnified view of a valve leaflet of a medical deviceaccording to an embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

The following provides a detailed description of exemplary embodimentsof the invention. The description is not intended to limit the inventionin any manner, but rather serves to enable those skilled in the art tomake and use the invention.

A medical device according to the invention provides a valve forregulating fluid flow through a body vessel. The device includes asupport frame and at least one valve leaflet. The leaflet provides ameans for regulating fluid flow through the body vessel, and the supportframe provides a surface to which the valve leaflet is attached.

A wide variety of support frames are known in the medical technologyarts, and any suitable support frame can be utilized. The onlyrequirement is that the support frame provide a surface to which thevalve leaflet can be attached and function as described herein.

As described below, the support frame advantageously has radiallycompressed and radially expanded configurations. Such a support framecan be implanted at a point of treatment within a body vessel byminimally invasive techniques, such as delivery and deployment with anintravascular catheter. The support frame can optionally provideadditional function to the medical device. For example, the supportframe can provide a stenting function, i.e., exert a radially outwardforce on the interior wall of a vessel in which the medical device isimplanted. By including a support frame that exerts such a force, amedical device according to the invention can provide both a stentingand a valving function at a point of treatment within a body vessel.

The stent art provides numerous support frames acceptable for use in thepresent invention, and any suitable stent can be used as the supportframe. The specific support frame chosen will depend on numerousfactors, including the body vessel in which the medical device is beingimplanted, the axial length of the treatment site within the vessel, thenumber of valves desired in the medical device, the inner diameter ofthe vessel, the delivery method for placing the medical device, andother considerations. Those skilled in the art can determine anappropriate support frame based on these and other considerations.

The support frame can be self-expandable or balloon expandable. Thestructural characteristics of both of these types of support frames areknown in the art, and are not detailed herein. Each type of supportframe has advantages and for any given application, one type may be moredesirable than the other based on a variety of considerations. Forexample, in the peripheral vasculature, vessels are generally morecompliant and typically experience dramatic changes in theircross-sectional shape during routine activity. Medical devices forimplantation in the peripheral vasculature should retain a degree offlexibility to accommodate these changes of the vasculature.Accordingly, medical devices according to the invention intended forimplantation in the peripheral vasculature, such as prosthetic venousvalves, advantageously include a self-expandable support frame. Thesesupport frames, as is known in the art, are generally more flexible thanballoon-expandable support frames following deployment.

Suitable support frames can be made from a variety of materials and needonly be biocompatible or able to be made biocompatible. Examples ofsuitable materials include, without limitation, stainless steel, nickeltitanium (NiTi) alloys, e.g., nitinol, other shape memory and/orsuperelastic materials, polymers, and composite materials. Also,resorbable and bioremodellable materials can be used. As used herein,the term “resorbable” refers to the ability of a material to be absorbedinto a tissue and/or body fluid upon contact with the tissue and/or bodyfluid. A number of resorbable materials are known in the art, and anysuitable resorbable material can be used. Examples of suitable types ofresorbable materials include resorbable homopolymers, copolymers, orblends of resorbable polymers. Specific examples of suitable resorbablematerials include poly-alpha hydroxy acids such as polylactic acid,polylactide, polyglycolic acid (PGA), or polyglycolide; trimethlyenecarbonate; polycaprolactone; poly-beta hydroxy acids such aspolyhydroxybutyrate or polyhydroxyvalerate; or other polymers such aspolyphosphazines, polyorganophosphazines, polyanhydrides,polyesteramides, polyorthoesters, polyethylene oxide, polyester-ethers(e.g., polydioxanone) or polyamino acids (e.g., poly-L-glutamic acid orpoly-L-lysine). There are also a number of naturally derived resorbablepolymers that may be suitable, including modified polysaccharides, suchas cellulose, chitin, and dextran, and modified proteins, such as fibrinand casein.

Stainless steel and nitinol are currently considered desirable materialsfor use in the support frame due at least to their biocompatibility,shapeability, and well-characterized nature.

Suitable support frames can also have a variety of shapes andconfigurations, including braided strands, helically wound strands, ringmembers, consecutively attached ring members, zig-zag members, tubularmembers, and frames cut from solid tubes.

Examples of suitable support frames for use in medical devices accordingto the invention include those described in U.S. Pat. Nos. 6,464,720 toBoatman et al. for a RADIALLY EXPANDABLE STENT; 6,231,598 to Berry etal. for a RADIALLY EXPANDABLE STENT; 6,299,635 to Frantzen for aRADIALLY EXPANDABLE NON-AXIALLY CONTRACTING SURGICAL STENT; 4,580,568 toGianturco for a PERCUTANEOUS ENDOVASCULAR STENT AND METHOD FOR INSERTIONTHEREOF; and published application for United States Patent 20010039450to Pavcnik et al. for an IMPLANTABLE VASCULAR DEVICE, each of which ishereby incorporated by reference in its entirety for the purpose ofdescribing suitable support frames for use in medical devices accordingto the invention.

FIGS. 1, 1A, 2, and 3 illustrate a suitable support frame 10 for use ina medical device according to the invention. Support frame 10 isdescribed in detail in U.S. Pat. No. 6,508,833 to Pavcnik et al. for aMULTIPLE-SIDED INTRALUMINAL MEDICAL DEVICE, which is hereby incorporatedby reference in its entirety for the purpose of describing suitablesupport frames for use in medical devices according to the invention.This support frame 10 is described briefly herein as an example of asuitable support frame for use in medical devices according to theinvention.

The support frame 10 is made of resilient material, preferably metalwire formed from stainless steel or a superelastic alloy, such asnitinol. While round wire is depicted in the figures, other types, suchas flat, square, triangular, D-shaped, and delta-shaped wire, may beused to form the frame 10. In the illustrated embodiment, the frame 10comprises a closed circumference 12 of a single piece of material thatis formed into a device having a plurality of sides 14 interconnected bya series of bends 16. The illustrated embodiment includes four sides 14of approximately equal length. Alternative embodiments include frameswith sides of different lengths, and frames of any polygonal shape, suchas pentagons hexagon, and octagon shapes.

In the embodiment illustrated in FIGS. 1, 1A, 2 and 3, the bends 16interconnecting sides 14 comprise a coil 18 of approximately one and aquarter turns. The coil 18 produces superior bending fatiguecharacteristics over those of a simple bend in support frames formed ofstainless steel and most other standard materials. A simple bend, suchas a substantially orthogonal bend, may be more appropriate, however, ifthe frame is formed of nitinol or other superelastic alloy, because theformation of certain types of bends, such as coil 18, may actuallydecrease fatigue life of a superelastic material. The specific structurechosen for bend 16 should be one that minimizes bending fatigue for thematerial of which the support frame 10 is formed. Alternative bendembodiments include outward-projecting fillets and inward-projectingfillets comprising a series of curves. Fillets are well known in thestent art as a means for reducing stresses in bends.

The cross-sectional diameter of the wire selected will depend on thesize of the medical device and the application. Wire that is too stiffcan damage the vessel, not conform well to the vessel wall, and increasethe profile of the device when loaded in a delivery system prior todeployment. Wire that is not sufficiently stiff may not allow the valveleaflet to function as desired.

The single piece of material comprising the frame 10 is formed into theclosed circumference 12 by securing the first and second ends 20, 22with an attachment mechanism 24, such as a metal cannula. The ends 20,22 are inserted into the cannula 24 and secured with a bonding element26, such as solder, an adhesive, or other suitable bonding element.Also, a mechanical bond can be formed between the ends 20, 22 andattachment mechanism 24 by crimping, deformation of adjacent elements,or any other suitable technique. Also, the ends 20, 22 can be joineddirectly to each other without addition of an attachment mechanism, suchas by soldering, welding, or other suitable methods to join material.Also alternatively, the frame 10 can be fabricated as a single piece ofmaterial by stamping or cutting a pattern from a sheet such as with alaser, fabricating from a mold, or some similar method of producing aunitary frame.

FIG. 1 illustrates the frame 10 in a first configuration 35 in which allcorners 30, 32, 34, 36 of the polygon and each of the sides 14 generallylie within a single flat plane. To resiliently reshape the frame 10 intoa second configuration 45, shown in FIG. 2, the frame 10 is foldedtwice, first along one diagonal axis 38 with opposite bends 30, 36 beingbrought into closer proximity with respect to each other, followed byopposite bends 32, 34 being folded toward each other and brought intocloser proximity. The second configuration 45 has two opposite bends 30,36 oriented at the first end 40 of the frame 10, while the otheropposite bends 32, 34 are oriented at the second end 42 of the frame 10and rotated approximately 90° with respect to bends 30, 36 when viewedin cross-section.

When deployed in a lumen 44 of a vessel 46, as illustrated in FIG. 2,the support frame 10 in the second configuration 45 exerts a radiallyoutward force on the interior wall 48 of the vessel 46. The bendingstresses introduced to the frame 10 by the first and second foldsrequired to form the second configuration 45 apply force radiallyoutward against the vessel wall 48 to hold the frame 10 in place andprevent vessel closure. Absent any significant plastic deformationoccurring during folding and deployment, the second configuration 45,when not in the vessel 46 or subject to other constraining means, willat least partially return to the first configuration 35, although somedeformation can occur depending on the material used. It is alsopossible to plastically deform the frame 10 into the secondconfiguration 45, such that it does not unfold when restraint isremoved. This might be particularly desirable if the device is made fromnitinol or a superelastic alloy.

As illustrated in FIG. 3, the frame 10 is formed into a thirdconfiguration 55 for loading into a delivery device 50, such as acatheter. In the third configuration 55, adjacent sides 14 a, 14 b aregenerally beside each other in close proximity and extend generallyalong the same axis. To advance and deploy the support frame 10 from thedistal end 52 of the delivery device 50, a pusher 54 is placed into thecatheter lumen 56. When the frame 10 is fully deployed within a vessel,it assumes the second configuration 45 as illustrated in FIG. 2. Thesides 14 of the frame 10, being made of resilient material, conform tothe shape of the vessel wall 48 such that when viewed on end, the frame10 has a generally circular appearance when deployed in a round vessel.As a result, sides 14 are arcuate or slightly bowed out to betterconform to the vessel wall 48.

FIGS. 4 and 5 illustrate a medical device 100 according to a firstembodiment of the invention. The device 100 includes a support frame 110and a valve leaflet 170 attached to the support frame 110. In thisembodiment, the support frame 110 is the support frame 10 illustrated inFIGS. 1, 1A, 2, and 3.

The valve leaflet 170 comprises a section of material, such as a sheet,that is attached to the support frame 110. The valve leaflet 170 can beformed of any suitable material, and need only be biocompatible or beable to be made biocompatible. The material can advantageously be formedof a flexible material. Examples of suitable materials for the valveleaflet 170 include natural materials, synthetic materials, andcombinations of natural and synthetic materials. Examples of suitablenatural materials include extracellular matrix (ECM) materials, such assmall intestine submucosa (SIS), and other bioremodellable materials,such as bovine pericardium. Other examples of ECM materials that can beused in the prosthetic valves of the invention include stomachsubmucosa, liver basement membrane, urinary bladder submucosa, tissuemucosa, and dura mater. Examples of suitable synthetic materials includepolymeric materials, such as expanded polytetrafluoroethylene andpolyurethane. ECM materials are particularly well-suited materials foruse in the valve leaflet 170, at least because of their abilities toremodel and become incorporated into adjacent tissues. These materialscan provide a scaffold onto which cellular in-growth can occur,eventually allowing the material to remodel into a structure of hostcells.

The valve leaflet 170 is attached to the support frame 110 in anysuitable manner. As illustrated in FIGS. 4 and 5, sutures 172 can beused for the attachment. Alternatively, the valve leaflet 170 can beattached to the support frame 110 by other means for attaching, such asadhesives, heat sealing, tissue welding, weaving, cross-linking, or anyother suitable means for attaching. The specific means for attachingchosen will depend at least upon the materials used in the valve leaflet170 and the support frame 110.

The valve leaflet 170 is moveable between first and second positionswhen the device 100 is placed within a body vessel 146. In the firstposition, illustrated in FIG. 4, the leaflet 170 permits fluid flow in afirst direction, represented by arrow 174, to flow through the device100. The pressure created by the flow of fluid exerts a force on oneface of the leaflet 170, forcing it toward vessel wall 148. In thesecond position, illustrated in FIG. 5, the leaflet 170 substantiallyprevents fluid flow in a second, opposite direction, represented byarrow 176 from flowing through the device 100. The valve leaflet 170moves to the second position when a pressure change and/or reversal offlow direction exerts a force on an opposite face of the leaflet 170 andforces the leaflet 170 away from the vessel wall 148 and across thelumen 144 of the vessel 146. The first position of the valve leaflet 170can be considered an open position, and the second position can beconsidered a closed position. By moving between these two positions, theleaflet 170 provides a valving function to the medical device 100,allowing it to regulate fluid flow through the medical device 100, andconsequently the vessel 144.

The medical device 100 illustrated in FIGS. 4 and 5 is a prostheticvalve, and can be used as a prosthetic venous valve. In this capacity,the device 100 is placed in a vein to regulate the flow of blood throughthe vein. It is believed that the valve leaflet 170 moves to the firstposition, illustrated in FIG. 4, during systole in which the heartforces blood through the vein in the first direction 174. Duringdiastole, the leaflet 170 moves to the second position, illustrated inFIG. 5, to substantially prevent fluid flow in the second, oppositedirection 176. It is believed that a pressure change and reversal offlow direction occurs during the change from systole to diastole, andthe valve leaflet 170 changes position in response to these changes.Flow in the second opposite direction 176 is commonly referred to asretrograde flow.

The leaflet 170 substantially, but not entirely, prevents fluid flow inthe second, opposite direction 176 for at least two reasons. First, asthe valve leaflet 170 moves from the first position to the secondposition, a time period passes before the valve leaflet is in the secondposition, and some retrograde flow may pass through the device 100during this time. Second, the medical device 100 includes an opening 180that permits a controlled amount of fluid flow to pass through themedical device 100 in the second, opposite direction 176.

The opening 180 provides a passageway through which a controlled amountof retrograde flow 176 can pass when the leaflet 170 is in the secondposition. The retrograde flow 176 passing through the opening 180 mayfacilitate closure of the valve by allowing some of the retrograde flow176 to continue moving past the leaflet 170. Also, the opening 180provides an escape through which blood can move to prevent poolingduring periods in which the valve leaflet 170 is in the second, orclosed, position.

The retrograde flow 176 that passes through the opening 180 when thevalve leaflet 170 is in the second position is controlled by the overalldimensions and configuration of the opening 180. A larger opening 180allows a greater amount of retrograde flow 176 to pass through themedical device 100, while a relatively smaller opening 180 will allow arelatively lesser amount of retrograde flow 176 to pass. The dimensionsand configuration of the opening 180 can be optimized based upon thevessel in which the device 100 is placed. The size and configurationselected will depend on several factors, including the vessel size,typical flow volumes and rates, and others. The opening 180 isadvantageounsly sized to allow a desired amount of retrograde flow passthrough the opening 180 during periods of retrograde flow 176. Theopening 180 should be small enough, though, to still allow the leaflet170 to substantially prevent retrograde flow 176 to pass through thedevice while in the second position. Thus, the opening 180 isadvantageously sized so as to not allow a majority of retrograde flow176 to pass through the opening 180. Thus, the total open area of theopening 180 is, at a maximum, less than the cross-sectional area of thevessel lumen 144. As used herein, the term “total open area”, inrelation to the opening, refers to the total area of the opening 180when the entire perimeter of the opening 180 lies in the same plane.

The opening 180 can be advantageously sized to mimic the degree ofretrograde flow—the leakiness—that is present in a natural valve locatedat the point of treatment in the body vessel. Accordingly, thedimensions of the opening 180 can be determined and optimized based uponthe vessel in which the device 100 is to be placed. For venous valveapplications, the total open area of the opening 180 is advantageouslyless than about 50% of the cross-sectional area of the vessel at theintended point of deployment. More advantageously, the total open areaof the opening 180 is less than about 25% of the total cross-sectionalarea of the vessel at the intended point of deployment. In one example,a device is configured for placement in a vessel having a totalcross-sectional area of about 50 mm². In this example, the opening has atotal open area of about 20 mm². Also for venous valve applications, acircular opening with a diameter of between about 0.5 and about 3.0 mmhas been found to be suitable. In a specific venous valve example, acircular opening with a diameter of about 1 mm has been found to besuitable. In another specific venous valve example, a circular openingwith a diameter of about 2 mm has been found to be suitable.

FIG. 6 illustrates a medical device 200 according to a second embodimentof the invention. In this embodiment, the leaflet 270 spans the entiresupport frame 210, and includes a slit 290 that defines an aperture inthe leaflet 270. The leaflet 270 opens and closes the slit 290 to permitflow in a first direction and substantially prevent flow in a second,opposite direction, i.e., retrograde flow, by moving the slit from afirst open position to a second closed position. The slit 290 can beoriented relative to the frame 210 as shown, or in any other suitableorientation.

In this embodiment, the medical device 200 includes multiple openings280, 282 for allowing a controlled amount of retrograde flow to passthrough the device 200 when the slit 290 is in the second, closedposition. Each of the openings 280, 282 is as described above for thefirst embodiment and the total cumulative open area of the openings 280,282 is, at a maximum, less than the cross-sectional area of the vessel246 at the intended point of deployment. Also in this embodiment, anedge 277 of the leaflet 270 and a portion of the support frame 210cooperatively define each opening 280, 282. This configuration isparticularly desirable in devices with leaflets formed ofbioremodellable materials, such as ECM materials, or other materialsthat can become adhered to or incorporated into a vessel wall 246following repeated and/or prolonged contact between the leaflet 270 andwall 246. In these embodiments, the opening reduces the overall surfacearea of the valve leaflet that contacts the vessel wall as the valveleaflet moves between the first and second positions. It is believedthat this reduction in surface area may reduce or eliminate thepossibility that the valve leaflet would become adhered to orincorporated into the vessel wall. Also, this positioning of the openingrelative to the support frame prevents stress that might be placed onthe valve leaflet during movement of the resilient support frame if theopening were not present. This may prevent damage to the valve leaflet.Thus, in the embodiment illustrated in FIG. 6, each of the openings 280,282 permits retrograde flow to pass through the medical device 200 whenthe slit 290 is in the closed position, and protects the leaflet 270 byspacing it away from the vessel wall 246. It is understood that, whiletwo openings 280, 282 are illustrated in this embodiment, the device 200could include only a single opening, or more than two openings.

FIG. 7 illustrates a medical device 300 according to a third embodimentof the invention. In this embodiment, the device 300 includes twoleaflets 346, 348 that are attached to the support frame 310. Eachleaflet 346, 348 has a free edge 350, 352 that is not attached to thesupport frame 310. The free edges 350, 352 cooperatively define valveorifice 392. The leaflets 346, 348 are both movable between first andsecond positions. In the first position, illustrated in FIG. 7, theorifice 392 is open and allows fluid flow through the device 300 in afirst direction, represented by arrow 374. In the second position, thefree edges 350, 352 of leaflets 346, 348 come together to close theorifice 392 and substantially prevent fluid flow through the device in asecond, opposite direction.

Each leaflet 346, 348 defines an opening 380, 382 that allows acontrolled amount of retrograde flow to pass through the medical device300 when the valve orifice 392 is closed. In this embodiment, each ofthe openings 380, 382 is defined entirely by the respective leaflet 346,348. Thus, one or more edges 394, 396 of the leaflets 346, 348 defineeach of the openings 380, 382.

FIG. 8 illustrates a medical device 400 according to a fourth embodimentof the invention. The device 400 of this embodiment is similar to thedevice illustrated in FIG. 7, except that each opening 480, 482 ispartially defined by an edge 494, 496 of a leaflet 446, 448 and aportion of the support frame 410. As described above, this configurationof the openings 480, 482 may be advantageous if the valve leaflets 446,448 are formed of a bioremodellable material or other material that canbecome adhered to or incorporated into a vessel wall following repeatedand/or prolonged contact between the valve leaflets 446, 448 and thevessel wall. Similar to the embodiment illustrated in FIG. 7, free edges450, 452 of leaflets 446, 448 define valve orifice 492 which opens andcloses to regulate fluid flow through the device 400.

FIG. 9 illustrates the device 400 of FIG. 8 inside a body vessel 456. InFIG. 9, the valve leaflets 446, 448 are in the second position in whichthe valve orifice 492 is closed. Thus, the device 400 as illustrated isin position to substantially prevent fluid flow in the second, oppositedirection. The openings 480, 482 permit a controlled amount ofretrograde flow 447 to flow through the device 440 while the valveorifice 492 is closed. Also, the openings 480, 482 are positioned on thedevice 400 such that the leaflets 446, 448 are protected fromsubstantial contact with the interior wall 448 of the vessel 456.

FIGS. 10, 11 and 12 illustrate a medical device 500 according to a fifthembodiment of the invention. In this embodiment, the device 500 includesa liner 590 secured to the perimeter 592 of the opening 580. As bestillustrated in FIG. 12, the liner 590 has a thickness 594 that spaces asurface 596 of the liner 590 from a surface 598 of the leaflet 548. Whenthe device 500 is deployed in a vessel, the surface 596 of the liner 590is the outermost surface of that portion of the device 500 with respectto the interior of the vessel. This configuration protects therespective valve leaflet 548 from the vessel wall.

The liner 590 can be made from a different material than the leaflets546, 548 on which it is disposed, or comprises a portion of the leaflets546, 548 that has been treated in a manner that prevents or reducesadhesion to and/or incorporation into the vessel wall as compared to theuntreated portions of the valve leaflets 546, 548. The liner 590 isadvantageously formed of a suitable biocompatible material, such as anappropriate plastic or metal, and is attached to the valve leaflets 546,548 by appropriate means for attaching such a material to the materialof the leaflets 546, 548, such as crimping, stitching, annealment, orother suitable means for attaching. Advantageously, as illustrated inFIGS. 10, 11 and 12, the liner 590 comprises a grommet attached to theperimeter 592 of the openings 580, 582.

FIGS. 13 and 14 illustrate a medical device 600 according to a sixthembodiment of the invention. This embodiment is similar to theembodiment illustrated in FIG. 8, except as described below. The medicaldevice 600 includes first 698 and second 699 liners disposed adjacentfirst 680 and second 682 openings that allow a controlled amount ofretrograde flow through the device 600 when the valve orifice 692 is ina closed position. The opening 680 is defined by an edge 694 of theleaflet 648 and a portion of the support frame 610, and the secondopening 682 is defined by an edge 696 of the leaflet 646 and anotherportion of the support frame 610.

The liners 698, 699 are attached to the support frame 610. The liner 698has a first surface 679 that extends at an angle to the support frame610 and substantially parallel to the vessel wall following deploymentof the medical device 600. Also, the liner 698 defines a passageway 677through which retrograde flow can proceed into the opening 680 and,ultimately, through the medical device 600. The liner 698 can beattached to the support frame 610 in a manner that creates an overlapregion that represents a length along an axis of the medical device 600in which the liner 698 overlaps the valve leaflet 648. The second liner699 advantageously has the same structure, and is attached to thesupport frame 610 in the same manner, as the first liner 698.

FIG. 15 illustrates a medical device 700 according to a seventhembodiment of the invention. This embodiment is similar to theembodiment illustrated in FIGS. 4 and 5, except as detailed below. Thus,the medical device 700 includes a support frame 710 and a valve leaflet770 attached to the support frame 710. An opening 780 in the valveleaflet 770 allows a controlled amount of retrograde flow, representedby arrow 776, to flow through the medical device 700 when the valveleaflet 770 is in a second, or closed, position.

In this embodiment, the support frame 710 includes a hinge 730. Thehinge 730 is a structural feature of the support frame 710, such as theillustrated eyelet, that allows the support frame to temporarily bend.Temporary bending of the support frame 710 is expected to allow thesupport frame to adjust to different loads placed on the support frame710 as fluid flow through the device 700 changes direction. For example,the support frame 710 may undergo a change in radial or other load whenthe flow direction changes. Also in this embodiment, the support frame710 includes barbs 732 to secure the device 700 to the interior wall 734of the vessel 736.

The hinge 730 can be any suitable structural feature that allows fortemporary bending of the frame 710, and the eyelet is but oneillustrative example. As illustrated in FIG. 16, a structurally weakersection 740 of the frame 710 can be used at a position on the supportframe 710 where bending is desirable, such as a position that will beadjacent the opening 780 in the finished medical device 700. Thestructurally weaker section 740 is able to bend to a greater degree thana relatively stronger section 742. The structurally weaker section 740can be weaker than the stronger section 742 due to a different geometry,such as a circular cross-sectional shape as opposed to a squarecross-sectional shape, or can comprise a thinner or narrower section ofmaterial than that in the relatively stronger section 742.

While the opening for allowing a controlled amount of retrograde flow toflow through the medical device is depicted as a circular or a partialcircular opening in some of the figures, it is understood that theopening can have any suitable shape, including square, triangular,ovoid, and teardrop shapes. FIGS. 17A, 17B, 17C and 17D illustratemedical devices 800 a, 800 b, 800 c, and 800 d, respectively, thatinclude openings 880 a, 880 b, 880 c, and 800 d, respectively, havingvarious suitable shapes. Specific examples of suitable shapes include asubstantially square opening 880 a (FIG. 17A), a substantiallytriangular opening 880 b (FIG. 17B), a substantially ovoid opening 880 c(FIG. 17C), and a teardrop-shaped opening 880 d (FIG. 17D). The actualshape chosen for the opening will depend on various factors, includingthe desired quantity of retrograde flow, the size and configuration ofthe leaflet(s) of the medical device, and the size and configuration ofthe vessel in which the medical device will be employed.

The opening for allowing a controlled amount of retrograde flow throughthe medical device can be substantially covered by a flap created in aleaflet. A flap configuration may allow retrograde flow to proceedthrough the opening, and minimize or prevent any antegrade flow fromproceeding through the opening. As used herein, the term “flap” refersto a section of material that is connected to or integrally formed withadjacent material at one side or end, but is free of adjacent materialat another side or end. The flap is a moveable section of material thatis adjacent the opening. As the flap moves, it is able to temporarilyand substantially close the opening. FIG. 18 illustrates a medicaldevice 900 that includes an opening 980 defined by a flap 982 formed inthe leaflet 984. FIGS. 19A, 19B, 19C, 19D, 19E, and 19F illustratemedical devices 1000 a, 1000 b, 1000 c, 1000 d, 1000 e, and 1000 f,respectively, that include flaps 1081 a, 1081 b, 1081 c, 1081 d, 1081 e,1081 f, respectfully, of various suitable shapes. Specific examples ofsuitable shapes include a partial square flap 1081 a (FIG. 19A), apartial triangular flap 1081 b (FIG. 19B), a partial ovoid flap 1081 c(FIG. 19C), and a partial teardrop-shaped flap 1081 d (FIG. 19D). FIG.19E illustrates a partial rectangular flap 1081 e and FIG. 19Fillustrates a crescent-shaped flap 1081 f. The actual shape chosen forthe flap will depend on various factors, including the desired quantityof retrograde flow, the size and configuration of the leaflet(s) of themedical device, the desired ability of the flap to close, and the sizeand configuration of the vessel in which the medical device will beemployed.

The opening that permits a controlled amount of retrograde flow to passthrough the medical device can be positioned at various locations on theleaflet. The position on the leaflet may affect the quantity ofretrograde flow that proceeds through the opening, the flow dynamics ofretrograde flow that proceeds through the opening, and the quantity ofany antegrade flow that might proceed through the opening. Asillustrated in FIG. 20A, the opening 1180 a can be positioned distal toa centerline 1190 a of the leaflet 1144 a, relative to the valve orifice1192 a. The centerline 1190 a is an imaginary line that proceeds throughthe vertical midpoint of the valve leaflet 1144 a. As illustrated inFIG. 20B, the opening 1180 b can be positioned between a centerline 1190b and the valve 1192 b. FIG. 20C illustrates an embodiment in which acenterline 1190 d proceeds through the opening 1180 c. Also, thecenterline 1144 d can comprise a portion of the perimeter of the opening1180 d, as illustrated in FIG. 20D. If a flap embodiment is used, theflap can be positioned on the leaflet in a similar manner. The exactposition chosen for the opening and flap, if utilized, will depend onvarious factors, including the desired flow dynamics of retrograde flowpassing through the opening.

In all embodiments of the invention, the opening for allowing acontrolled amount of retrograde flow through the medical device can beformed by any suitable technique, including cutting and punching. Theflap, if used, can also be formed by these and other suitabletechniques. Furthermore, the opening can be formed prior to or followingattachment of the valve leaflet to the support frame.

FIG. 21 illustrates a method of forming an opening 1280 for allowing acontrolled amount of retrograde flow to flow through a medical deviceaccording to the invention. Two cuts are made in the valve leaflet 1244along intersecting lines 1260, 1262. The resulting flaps 1264, 1266,1268, 1270 are folded back and can be secured to the valve leaflet 1244by any suitable technique, or can be trimmed away.

The valve leaflet can be reinforced at one or more locations along theperimeter of the opening that permits a controlled amount of retrogradeflow to flow through the medical device. In use, the opening will beexposed to a variety of forces in a dynamic environment. A reinforcementmay increase the durability of the valve leaflet at the location of theopening by preventing tearing or other unintended expansion of theopening.

Any suitable means for reinforcing the valve leaflet can be used. Theliners, such as the exemplary grommet described and illustrated herein,are a suitable reinforcement. Also, as illustrated in FIGS. 22 and 23,one or more sutures 1370 can be placed on the valve leaflet 1344adjacent the opening that permits a controlled amount of retrograde flowthrough the device. The suture(s) 1370 can be drawn tight to gather aportion of the leaflet 1344. In the embodiment illustrated in FIG. 22,the sutures 1370 are placed at various locations around a circularopening 1380 a. In FIG. 23, the sutures 1370 are placed at respectiveends of a slit-like opening 1380 b.

The preceding provides a detailed description of exemplary embodimentsof the invention and includes the best mode for practicing theinvention. The description of embodiments is intended only to enable oneof ordinary skill in the art to make and use the invention, and is notintended to limit the invention in any manner.

1. An implantable medical device that provides a valve for regulatingfluid flow through a body vessel, comprising: a support frame; at leastone leaflet attached to the support frame and being moveable between afirst position that permits said fluid flow in a first direction and asecond position that substantially prevents said fluid flow in a second,opposite direction, one of the at least one leaflet having a leafletfree edge not attached to the support frame, first and second opposingsurfaces and defining an opening extending through the one leaflet fromthe first surface to the second opposing surface that permits acontrolled amount of fluid flow in the second, opposite direction toproceed through the opening when the one leaflet is in the secondposition, the opening spaced from the leaflet free edge on the oneleaflet and having an opening first side edge defined by the one leafletand an opening second side edge defined by the one leaflet and disposedon the one leaflet opposite the opening first side edge; a moveable flapintegrally formed with a portion of the one leaflet adjacent the openingfirst side edge and free of the one leaflet at the opening second sideedge, the moveable flap adapted to temporarily and substantially closethe opening.
 2. The implantable medical device according to claim 1,wherein the at least one leaflet is formed of a bioremodellablematerial.
 3. The implantable medical device according to claim 2,wherein the bioremodellable material comprises an extracellular matrixmaterial.
 4. The implantable medical device according to claim 3,wherein the bioremodellable material comprises small intestinesubmucosa.
 5. The implantable medical device according to claim 1,wherein the opening has a total open area; and wherein the total openarea of the opening is sized to be less than the cross-sectional area ofsaid body vessel at a desired point of treatment in said body vessel. 6.The implantable medical device according to claim 1, wherein the openinghas a total open area; and wherein the total open area of the opening issized to be less than about 50% of the cross-sectional area of said bodyvessel at a desired point of treatment in said body vessel.
 7. Theimplantable medical device according to claim 1, wherein the opening hasa total open area; and wherein the total open area of the opening issized to be less than about 25% of the cross-sectional area of said bodyvessel at a desired point of treatment.